docs: def add_bridge_port(name, port, promisc=False):
      ''' Add a port to the named openvswitch bridge '''
      log('Adding port {} to bridge {}'.format(port, name))
      subprocess.check_call(["ovs-vsctl", "--", "--may-exist", "add-port",
                             name, port])
      subprocess.check_call(["ip", "link", "set", port, "up"])
      if promisc:
          subprocess.check_call(["ip", "link", "set", port, "promisc", "on"])
      else:
          subprocess.check_call(["ip", "link", "set", port, "promisc", "off"])